Making gold by nuclear reactions -- what efficiency?

[lpetrich]

This was one of the alchemists' big quests, and it is evident that it is impossible with the methods that they had available. But how feasible is it to do that with nuclear reactions? Especially nuclear reactions that start with relatively common materials, like hydrogen or carbon or silicon or iron or lead.

This question can be broken down into parts.

How energy-efficient are particle accelerators? Efficiency being how much energy goes into a particle divided by the wall-plug electrical energy involved in accelerating that particle. In effect,
(particle flux) * (energy per particle) / (total energy consumed by the accelerator)

I'd only need this for accelerators that do a few MeV per unit charge, because those are what one would need for nuclear reactions.

What are the most suitable sorts of reactions? Direct acceleration of nuclei into targets? Or releasing neutrons by spallation and then using those neutrons. What branching fractions to such reactions typically have?

I'm asking this here because it's hard to find the appropriate numbers, like for particle-accelerator energy efficiency. If this forum is an unsuitable place for this question, then feel free to move it elsewhere.

 

[SteamKing]

This was one of the alchemists' big quests, and it is evident that it is impossible with the methods that they had available. But how feasible is it to do that with nuclear reactions? Especially nuclear reactions that start with relatively common materials, like hydrogen or carbon or silicon or iron or lead.

This question can be broken down into parts.

How energy-efficient are particle accelerators? Efficiency being how much energy goes into a particle divided by the wall-plug electrical energy involved in accelerating that particle. In effect,
(particle flux) * (energy per particle) / (total energy consumed by the accelerator)

I'd only need this for accelerators that do a few MeV per unit charge, because those are what one would need for nuclear reactions.

What are the most suitable sorts of reactions? Direct acceleration of nuclei into targets? Or releasing neutrons by spallation and then using those neutrons. What branching fractions to such reactions typically have?

I'm asking this here because it's hard to find the appropriate numbers, like for particle-accelerator energy efficiency. If this forum is an unsuitable place for this question, then feel free to move it elsewhere.

There's a whole wiki article about this:

http://en.wikipedia.org/wiki/Synthesis_of_precious_metals

The short answer is this transmutation process is incredibly expensive, such that the value of the metal produced could pay back only a tiny fraction of the cost involved in its production. More often than not, the isotopes of the precious metals produced are radioactive and thus could not be sold without exposing people to radiation.

 

[e.bar.goum]

If we could do this, nuclear physics would be a much better funded field.

"Hey Bob, we need a new detector!"

"Sure, let me fire up the accelerator!"

That'd be great.

 

[mfb]

Especially nuclear reactions that start with relatively common materials, like hydrogen or carbon or silicon or iron or lead.

You'll have to start with something close to gold, otherwise the energy requirements are really bad, the fraction of gold very low and you produce all sorts of nasty radioisotopes.
Platinum is sometimes a bit cheaper, sometimes more expensive, but it's not really an interesting material to transform to gold. Mercury (cheap) has a proton more than gold.

In the range up to a few MeV, you can use electrostatic acceleration, the efficiency of the acceleration itself is close to 100% and the wall plug -> acceleration efficiency is still good enough to not worry about it. It is still not reasonable, however. At ~$40/g and about 12 cents per kWh (US-value), you can spend at most 2.5 MeV per gold atom. There is no way to get one atom of gold with that energy. Just electricity costs ruin the plan.

 

[arivero]

You need to use isotope 201 of Mercury AND you need to have a way to induce alpha-decay. This is the real problem, no energy. Most elements beyond Iron-Nickel are really metastable for alpha-decay, it is just that the decay time should be higher that the lifespan of the universe.

I can not tell why most people think that there is an energy requeriment "really bad".

Assuming that you have a method (say, collisions, thermal, gamma excite, whatever) to enhance alpha decay of 201Hg and to do not enhance the subsequent decay of other elements, you are done. You decay 201Hg to 197Pt and then it will beta decay by itself to your beloved 197Au.

(PS the wikipedia article http://en.wikipedia.org/wiki/Isotopes_of_mercury#cite_note-10 notes that this decay is "believed" to exist).

 

[arivero]

At ~$40/g and about 12 cents per kWh (US-value), you can spend at most 2.5 MeV per gold atom. There is no way to get one atom of gold with that energy. Just electricity costs ruin the plan.

With 201Hg--->197Pt--->197Au

201 Hg -> 197Au ---> 200.970277- 196.9665516 = 4.0037254 amu
4 He is 4.0026032 amu
The diference is 4.0037254-4.0026032=0.0011222 amu = 1.04532 MeV produced by gold atom.

I can use my transmutator to power yours :D

EDIT: ok, I see now that your argument is that you can allow, from market prices, to waste up to 2 MeV per atom... but the point is that you do not waste them! The reaction is exoenergetic, you need the energy to jump the barrier, but you recover the energy (and one extra MeV) after you have got the gold.

 

[arivero]

Let me add, if you look in this forum the keywords 201 Hg, you will find that the question has been already reviewed from time to time.

So there is a meta-question: Why do we keep "lying" by giving the simple answer of "energetically unfeasible"? In this case it is valid because the OP ask to start from Iron, which is in the peak of the nuclear stability curve. But we answer the same even when asked to start from elements lower in the curve! I think that we do it because we know that practically any attempt to do this conversion is a scam (red mercury comes to mind) and we try to protect the OPs either of being scammed, or of the temptation of becoming scammers themselves.

 

[lpetrich]

So starting with mercury will make it relatively easy, even though it takes around 2.5 MeV per atom. It's easy to estimate how much it costs to make gold with that energy input.

Gold is often measured in troy ounces: 1 troy ounce = 31.1034768 grams
Gold has exactly one stable isotope: Au-197 with atomic weight: 196.9666 amu
Avogadro's number: 6.02214*10²³
1 troy ounce of gold = 9.51*10²² Au-197 atoms

1 electron volt = 1.602177*10^-19 joules
Energy per atom = 4.01*10^-13 joules

Energy per troy ounce of gold-197: 3.81*10¹⁰ joules

I'll use US electricity prices from U.S. Energy Information Administration (EIA) - Data > Sales (consumption), revenue, prices & customers > Average retail price of electricity to ultimate customers > By end-use sector, by provider, latest year
Residential: 11.88, Commercial: 10.09, Industrial: 6.67 cents/kWh

These prices gives $1300, $1100, and $700 per troy ounce.

Checking Gold Price: Latest Price & Chart for Gold - NASDAQ.com recent gold prices have been around $1170 / troy ounce

So at 100% efficiency, one would need relatively cheap electricity to compete.

I still haven't been able to find typical numbers for the energy efficiency of small particle accelerators.

 

[arivero]

So starting with mercury will make it relatively easy, even though it takes around 2.5 MeV per atom.

No, no... Sorry I induced you to misinterpret the statement of mfb. He was just telling that with current electricity prices, you could at most to push 2.5 MeV into each atom. You are doing some similar calculation. I am in doubt that the calculations are realistic, for sure Hg is not cheap either, and you must put some preprocessing.

To be clear: no method is known to produce such transmutation in an industrial, regular way.

Consider also that the relative abundance of atoms with similar weight is similar. The supply of Hg is also scarce.

The existence of a cataliser for this transmutation has been a well-known scam for hundred of years. As part of the tradition, the cataliser is always named "red mercury", and it is still used with this name in the camerunese scam of "wash-wash", where some black papers are transmuted into dollar or euro bills.

 

[mfb]

Assuming that you have a method (say, collisions, thermal, gamma excite, whatever) to enhance alpha decay of 201Hg and to do not enhance the subsequent decay of other elements, you are done.

Assuming I have some magic device that allows easy hydrogen fusion at room temperature, I can make as many fusion power plants as I like. There is just some tiny detail missing...

Particle accelerators can be used to induce nuclear reactions, but then you will need energy. A lot of energy. More than 2.5 MeV per gold atom of the right isotope.

I found mercury prices in the range of 50 to 100 USD/kg, less than 10% of the gold price. If you do isotope separation, you can sell most of the mercury back again. Well, it adds the cost of the isotope separation of course, probably more than the gold costs afterwards.Yes the 2.5 MeV per atom were calculated as the point where electricity costs equal the costs of the produced gold.

I still haven't been able to find typical numbers for the energy efficiency of small particle accelerators.

Good enough to not worry about it. Electrostatic acceleration is close to 100%.

 

[e.bar.goum]

I would place real money on the odds that isotopically pure 201Hg being more expensive than gold. It's only 13% of natural, and enrichment is expensive.

How expensive? Gold is just about the cheapest target material you use in Nuclear physics.

 

[arivero]

Yes the 2.5 MeV per atom were calculated as the point where electricity costs equal the costs of the produced gold.

Actually the figure is not so bad if we had the magical device to put all the energy to excite the alpha... To be in the range of hours to minutes in decay time, we should need a excitation about 6 MeV, and we already have 1MeV from the difference, so just 5MeV by atom could do the break-even. We loss money at the current price, but we could reconsider if energy price halves or gold price doubles. And we could use the recovered energy, at least as thermal source for something, it does not need to be a full loss.

Of course without magic the system would do a nice spectrum of gamma instead of the desired alpha.

 

[arivero]

I would place real money on the odds that isotopically pure 201Hg being more expensive than gold. It's only 13% of natural, and enrichment is expensive.

How expensive? Gold is just about the cheapest target material you use in Nuclear physics.

Besides, as the only argument to do the try is for sentimental reasons, I think that if we are at it, enrichment should be done in the traditional alchemical way: by repeating distillation of Hg in a multiple horned distillation column or alambic until the operator becomes mad as a hat-maker due to the vapours.

 

[e.bar.goum]

Also! Recall that there is only a certain probability of anyone given reaction occurring. Most of the time, you'll just get elastic scattering. So that'll severely limit your efficiency.

 

[lpetrich]

How expensive? Gold is just about the cheapest target material you use in Nuclear physics.

Why is that? Lead has similar numbers of protons and neutrons and is MUCH less expensive.

 

[e.bar.goum]

There is only one stable isotope of gold, unlike lead, which has four, and quite a few long-lived isotopes. 208Pb is only 52% abundant, 206 and 207Pb have abundances ~20%

So if you want to study lead, you first have to enrich it to get isotopically pure samples.

 

[nikkkom]

It might be worthwhile to extract gold from spent nuclear fuel.

Sure, reprocessing is expensive, but if you _already_ do it for other reasons such as extraction of uranium and plutonium, reduction of the volume of waste, you can add more steps to the process and extract gold or other expensive elements.

Gold is easy-ish since it has no long-lived radioactive isotopes, so you'd need only chemical separation. Compare to platinum, where Pt-193 with half-life of 50 years makes recovered metal very dangerous.

Other suitable expensive metals are Rhenium, Osmium, Ruthenium.

I suspect that after more detailed accounting, it would still be uneconomical, though.

 

[nikkkom]

Wiki has an article on this:

http://en.wikipedia.org/wiki/Synthesis_of_precious_metals

 

[TrueGormagon]

Hello, this will be my first reply on the forum.

So, I think the efficiency energy wise and time wise of transmuting elements into something like gold, as far as we know, is beyond inefficient. If one had access to free energy even, I think it would be a lot more efficient to pursue asteroid mining once accessible supplies of minerals on Earth are exhausted. The asteroids in near Earth orbit could contain more precious metal and industrial metal then has been mined in human history, (All the gold in human possession put together would make a cube with sides about 18.2 meters in length, (60 feet) or fill 3 Olympic swimming pools I do believe.) in fact asteroids are the source of such minerals in the Earth's crust, however this leads to the same outcome as the discovery of efficient alchemy: The purchasing power of precious metal plummets to nill, making the reestablishment of an economy backed by precious metal (Today 95% of money is actually debt in the form of magical numbers we view with value called bank credit.) implausible as everyone can have heated golden toilet seats.

 

[mfb]

The asteroids in near Earth orbit could contain more precious metal and industrial metal then has been mined in human history,

Sure, but the same is true for the Earth's crust. The average cubic kilometer has several tons of gold, platinum, more than 100 tons of silver, millions of tons of iron and various other valueable materials. There are billions of tons of gold in the upper part of the crust. The challenge is the separation from all the irrelevant stuff.

 

[TrueGormagon]

Sure, but the same is true for the Earth's crust. The average cubic kilometer has several tons of gold, platinum, more than 100 tons of silver, millions of tons of iron and various other valueable materials. There are billions of tons of gold in the upper part of the crust. The challenge is the separation from all the irrelevant stuff.

True yes, there is still enough mineral wealth left in the crust of Earth to keep us going for decades at least but more likely centuries or millennium especially by sifting through millions of tons of worthless minerals to extract things like gold or so called R.E.E's like neodymium, a 1995 survey of the U.S guesstimated about 1.2 trillion dollars (At the time) worth left in the U.S. (not even close to enough to pay off the debt of the nation until metals purchasing power explodes, not that you can actually pay off debt without crashing the economy, its a really stupid system we use in the world today.) alone in gold, silver, copper, lead and zinc. And when you consider that gold is forever and iron/nickle can be recycled again and again we are pretty set.

See article-
http://pubs.usgs.gov/info/assessment/And we may finally figure out the engineering required to mine deeper inside the Earth or on the ocean floor itself, not only for naturally occurring mineral deposits but cargo from the estimated 3 million shipwrecks on the ocean floor. I think we should pursue deep ocean mining. But companies like Planetary resources Inc. are already pursuing plausible asteroid mining. I'm not sure human greed has the patience to sift Earth's crust or the ocean for its wealth. Tis sad we know more about space then our deep oceans.You have to admit though a heated golden toilet seat would be awesome.

 

[mfb]

But companies like Planetary resources Inc. are already pursuing plausible asteroid mining.

They still face the same problem - the asteroids are mainly worthless stuff. The concentration of valuable materials can be higher, but you still have to get your mining equipment on the asteroid, extract the valuable material, and get the extracted materials back to earth. Spaceships have to get significantly cheaper before this becomes viable.

Launching 1kg of mass to space costs roughly the same as 1kg of gold on Earth (the comparison was better a few years ago, but the order of magnitude is still right).

 

[nikkkom]

You have to admit though a heated golden toilet seat would be awesome.

Actually, for me it would be a sign of the owner being an idiot.

Clever rich people do not indulge in stupid displays of extremely expensive trinkets.

 

[TrueGormagon]

They still face the same problem - the asteroids are mainly worthless stuff. The concentration of valuable materials can be higher, but you still have to get your mining equipment on the asteroid, extract the valuable material, and get the extracted materials back to earth. Spaceships have to get significantly cheaper before this becomes viable.

Launching 1kg of mass to space costs roughly the same as 1kg of gold on Earth (the comparison was better a few years ago, but the order of magnitude is still right).

Yes, I believe there are three companies that NASA is contacting out to or some such arrangement, moving space travel into the private sector, including Boeing and Space Ex. Its coming. Automation will make things a lot easier, and establishing the infrastructure in the first place.

However, similar principles apply to the nuclear transmutation idea, is it worth the initial investment? Is there someone willing to make the investment in the first place? Ocean mining. We have the technology and the engineering, but the monetary investment into the infrastructure is the issue. There is a company I forget the name that hunts deep sea wrecks in search of treasure ships from varying times, like Spanish vessels returning from Peru or WWII transports sunk by U boats and whatnot, they won't bother with the operation unless the estimated value is $50,000,000 U.S or higher because it costs around $2,000,000-4,000,000 just to find it, collect it and pay legal fees.

Actually, for me it would be a sign of the owner being an idiot.

Clever rich people do not indulge in stupid displays of extremely expensive trinkets.

Its called humor.

The gold would not be a representation of wealth anymore, well it has industrial and technological applications its monetary 'value' primarily comes from its scarcity. When it is no longer scarce, it will cease to have monetary value in the eyes of humans.

 

[lpetrich]

You have to admit though a heated golden toilet seat would be awesome.

There are lots of things that people could use gold for if it was as common as wood. Like use it for weights. Gold is more dense than lead, but lead is the proverbially dense element because it's much more common and thus much more easily used in applications where one needs high density.

Actually, for me it would be a sign of the owner being an idiot.

Clever rich people do not indulge in stupid displays of extremely expensive trinkets.

However, many people do similar things -- it's called "conspicuous consumption".

 

[e.bar.goum]

Gold is more dense than lead, but lead is the proverbially dense element because it's much more common and thus much more easily used in applications where one needs high density.

This is my problem with solid gold toilet seat. You'd have to invent some kind of mechanism to lift it up and down...

 

[mfb]

It would also get scratches soon.
Gold might help against bacteria.

 

[nikkkom]

There are lots of things that people could use gold for if it was as common as wood. Like use it for weights.

You can use tungsten, it has almost the same density.

 

[e.bar.goum]

You can use tungsten, it has almost the same density.

And is rather less likely to deform if you drop them.

 

[TrueGormagon]

If lead was not so toxic and soft lead would work pretty well for weights. Or Osmium...